Sectional lifting door system

A sectional lifting door system, comprising a shaft, a torsional spring, at least one cable drum, at least one slat, at least one cable and a door operator, wherein the torsional spring is used for applying a specific preloaded torsion force on the shaft;

• the at least one cable drum is disposed on the shaft;
• one end of the at least one cable is connected to the at least one cable drum, and the other end of the at least one cable is connected to the at least one slat;
• the door operator is kinematically connected to the shaft and includes:
• a ratchet, connected to an output shaft, the ratchet including a plurality of tooth spaces, each tooth space including a bottom wall, a first flank and a second flank, an included angle between the first flank and the bottom wall being less than or equal to 90 degrees, and an included angle between the second flank and the bottom wall being greater than 90 degrees;
• a sleeve, fitted on the output shaft, the sleeve being kinematically connected to the shaft;
• and
• a pawl, disposed on the sleeve and selectively engaged with one of the plurality of tooth spaces of the ratchet, the pawl including a first surface and a second surface, the first surface being used for correspondingly contacting the first flank of the tooth space, the second surface being used for correspondingly contacting the second flank of the tooth space,
• wherein when the at least one slat is to be lifted, the output shaft is rotated so that the first flank of one of the plurality of tooth spaces of the ratchet is brought into contact with the first surface of the pawl, thereby driving the sleeve to rotate, and the sleeve further drives the shaft to wind the at least one cable around the at least one cable drum,
• wherein when the at least one slat is to be lowered, the output shaft is rotated so that the second flank of one of the plurality of tooth spaces of the ratchet is brought into contact with the second surface of the pawl, thereby driving the sleeve to rotate, and the sleeve further drive the shaft to unwind the at least one cable from the at least one cable drum;
• during a process of lowering the at least one slat, when a tensile force acting on the at least one cable drum is reduced, the second flank of one of the plurality of tooth spaces of the ratchet is disengaged from the second surface of the pawl so that rotation of the sleeve, the shaft and the at least one cable drum is stopped.